That usually means it is not the correct password, as Thunderbird is only reporting what the email host responds. Many email providers require a separate password for use with email clients, such as gmail, AOL, Verizon, and others. If you provide your email host, someone here may be able to assist, or you could contact your email provider.

Thanks for the reply David turns out I needed to upgrade my security setting to OAuth 2.0 in Mozillo-all good now